How does rising atmospheric CO2 affect marine organisms?

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Ocean Acidification and Warming Benefit an Arctic Primary Producer

Paper Reviewed
Hoppe, C.J.M., Flintrop, C.M. and Rost, B. 2018. The Arctic picoeukaryote Micromonas pusilla benefits synergistically from warming and ocean acidification. Biogeosciences 15: 4353-4365.

Micromonas pusilla is one of the most abundant picoeukaryote species in the Arctic Ocean. Although it is very small, this phytoplankton is increasingly recognized for its contribution to both primary and export production of carbon in the world's oceans. Consequently, there has been much interest with respect to the potential response of this marine organism to projected future changes in both temperature and seawater pCO2. And while much information has been gathered on the response of M. pusilla to these two variables individually, to date, little is known about their combined or synergistic effects. Thus, it was the objective of Hoppe et al. (2018) to determine just that.

Focusing on the growth and biomass build-up of M. pusilla, the team of three European researchers grew a strain of the picoeukaryote in a controlled-environment laboratory under four pCO2 levels (180, 380, 1000 and 1400 µatm) and two temperatures (2 and 6 °C) for a minimum of seven generations prior to sampling.

In presenting their findings, Hoppe et al. report that, individually, "both warming and [elevated pCO2] caused more efficient biomass build-up." However, they add that such beneficial effects manifested "even more strongly in combination." What is more, the researchers report that "elevated temperatures shifted the pCO2 optimum of biomass production to higher levels," where the pCO2 level associated with the peak growth response was 1000 µatm in 6°C water versus 380 ľatm in 2°C water.

Commenting on their work, Hoppe et al. write that "picoeukaryotes such as M. pusilla are considered to be potential winners of climate change: they are not only thriving in warmer, more stratified environments, which are predicted to further expand in the future, but [they] also seem to benefit from ocean acidification." Such positive findings add to the ever-growing list of studies reviewed on our website that demonstrate that ocean acidification and climate change are not the twin evils of the environment they are often made out to be.

Posted 7 November 2018